[Bug 1941622] Re: [SRU] Bump unmatched CPU clock rate to 1.2 GHz

[Heinrich Schuchardt]

>> 1) I assume this is a runtime change that happens after updating the u-boot
>> packages on an installed SiFive drive, right? Does the change happen instantly
>> after upgrade of the package? Or on next reboot?

The change is only visible after rebooting.

>> 2) The test case is not too clear about how one checks if the patch is in
>> effect or not. How can one confirm that the effective CPU clock speed is
>> now different? Is it just a matter of `cat /proc/cpuinfo`?

You can check that in U-Boot that the control device tree has the new
setting:

fdt addr $fdtcontroladdr
fdt print

For measuring the actual speed I used package glpk-utils.

I measured the execution time of the command

glpsol -m /usr/share/doc/glpk-utils/examples/tsp.mod

I suggest to check both before and after upgrade.

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Title:
  [SRU] Bump unmatched CPU clock rate to 1.2 GHz

Status in u-boot package in Ubuntu:
  Fix Released
Status in u-boot source package in Focal:
  Incomplete

Bug description:
  [Impact]

  Bump SiFive Unmatched CPU clock rate from 1.0 GHz to 1.2 GHz as used
  by upstream U-Boot.

  This is the maximum frequency that according to SiFive is stable on
  all boards.

  [Test Plan]

   * System with these patches boots, operates normally without
  overheating. CPU clock speed is increased form 1.0 GHz to 1.2 GHz.

  [Where problems could occur]

   * Overheating, instability, panics. (Should not occur according to
  the board vendor)

  [Other Info]
   
   * wgrant & multiple SiFive forum users report even 1.5 GHz to be stable

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